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Supported Features

This section describes features that are supported by SIP Proxy.


SIP Proxy is responsible for proxying SIP messages from external SIP user agents to the appropriate SIP Server. It is the responsibility of each external user agent to choose a SIP Proxy instance when sending a SIP message. Typically a deployment should have an overall configuration resulting in load balancing across the SIP Proxy instances.

Active Out-of-Service Detection

Each SIP Proxy instance pings each primary SIP Server using an OPTIONS message. If the primary SIP Server does not respond during a configured timeout, SIP Proxy starts to ping the backup SIP Server. If the backup SIP Server responds, the backup SIP Server address will be used as a destination for calls. If both the primary and backup SIP Server instances do not respond, SIP Proxy will mark this SIP Server HA pair as out-of-service and will not use it for calls; however, SIP Proxy will continue pinging them.

Related configuration options:

Overload Detection

SIP Proxy has the ability to control and restrict a dialog (incoming INVITE messages) rate. This feature is enabled by the overload-ctrl-dialog-rate configuration option. When the overload is detected, SIP Proxy rejects new INVITE requests by generating a 503 Service Unavailable error message.

SIP Address Binding

SIP Proxy uses the sip-address configuration option to identify on which network interface it should bind the SIP port. If this option is not set, SIP Proxy binds the SIP port on all network interfaces.

Error Handling

SIP Proxy can inform about errors and problems through:

  • Logs
  • SCI Alarms
  • HTTP Server interface

The following is the list of SIP Proxy log messages of level Standard:

Log Event ID Text Description
40000 SPR_OWN_PROXY_ADDR_NOT_FOUND Initialization failed, proxy address (host:port) is not found in the list
40001 SPR_SIPS_HA_PAIR_UNAVAILABLE SIP Server HA pair (primary host:port) is unavailable
40002 SPR_OTHER_PROXY_INSTANCE_DISCONNECTED SIP Proxy instance is disconnected
40003 SPR_ERROR_READING_CONFIG_DATA Error while reading configuration data
40004 SPR_PROXY_INITIALIZED SIP Proxy has initialized successfully
40005 SPR_HOST_NOT_RESOLVED Cannot resolve SIP Proxy host
40006 SPR_SIP_LISTENER_CANNOT_START Cannot start SIP listener
40007 PR_MGMT_LISTENER_CANNOT_START Cannot start Mgmt listener

Transport Layer Security

Starting with version, SIP Proxy supports secure communication for SIP traffic using the standard Transport Layer Security (TLS) protocol. Secure communication is supported between SIP Server and SIP Proxy, and between SIP Proxy and SIP endpoints (such as Media gateways, Session Border Controllers (SBC), Genesys Voice Platform, and agent phones), if configured. See Transport Layer Security for details.

Keep Alive for TCP Connections

Starting with version, SIP Proxy provides the ability to detect stale TCP connections between SIP Proxy and a SIP device using the TCP keep-alive mechanism. This functionality is recommended for those environments in which SIP endpoints are located behind a firewall that is configured to drop inactive TCP connections silently and without sending any notification to SIP Proxy. If SIP Proxy tries to use a stale connection to initiate a new call or to execute call control, the attempt would fail. As a result, the SIP endpoint is placed to out of service. See Keep Alive for TCP Connections for details.


  • Loop-detection check mechanism is not supported.
  • Strict routing is not supported.
This page was last edited on November 1, 2021, at 23:54.
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